Fish learn fear from their role models

Even fish have role models. In a new study, researchers paired up inexperienced fathead minnows (Pimephales promelas, pictured) with two types of mentors: a minnow raised in an environment free of predators or a minnow raised in a dangerous one simulated by the odors of predatory pike and sturgeon. Fish from dangerous environments were fearful of the smell of both unknown and familiar predators, whereas fish that grew up in safety hid when they smelled a known predator but were curious about new smells. Both types of fish passed on their fears to their protégés: Minnows that spent time with fish raised in dangerous environments were scared of all smells they came across, but those that learned from fish raised in safety feared only specific predators and took new experiences in stride, the team reports online this week in the Proceedings of the Royal Society B. The authors say this is the first experiment to show that environment can influence the social transmission of fear and reveals how risk aversion can be learned. The researchers also suggest their study may shed light on how fear disorders such as post-traumatic stress disorder (PTSD) develop in humans, which research shows can be influenced by social environment; PTSD symptoms can be acquired from friends or family who have suffered trauma, for example. www.glorybios.com